Given the user count is found by just counting the list, the following is sufficient. 
my @strings = (
    '8 changes by 4 users: user1 user2 user3 user4',
    '1 change by user1',
);

for (@strings) {
    if (/^(\d+) change(?: by|s by \d+ users:) (.*)/) {
        my $changes = $1;
        my @users = split ' ', $2;
        
        print "changes=$changes, users=".@users.", list=@users\n";
    }
    else {
        warn "Unrecognized string: $_\n";
    }
}

[download]
Outputs 
changes=8, users=4, list=user1 user2 user3 user4
changes=1, users=1, list=user1

[download]
- Miller

In reply to Re: Dynamic matching by wind
in thread Dynamic matching by flybd5

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